Supercritical fluid extraction of rare earth elements, thorium and uranium from monazite concentrate and phosphogypsum using carbon dioxide containing tributyl phosphate and di-(2-ethylhexyl)phosphoric acid

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• 作者：M. D. Samsonov ; T. I. Trofimov ; Yu. M. Kulyako…
• 关键词：supercritical fluid extraction ; microwave radiation ; rare earth elements ; thorium ; uranium ; carbon dioxide ; monazite concentrate ; phosphogypsum ; tributyl phosphate ; di ; (2 ; ethylhexyl)phosphoric acid
• 刊名：Russian Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：10
• 期：7
• 页码：1078-1084
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry;
• 出版者：Pleiades Publishing
• ISSN：1990-7923
• 卷排序：10

文摘

Supercritical fluid extraction (SCFE) using carbon dioxide containing tributyl phosphate (TBP), di-(2-ethylhexyl)phosphoric acid (D2EHPA) and their adducts with HNO₃ is applied for extraction of rare earth elements (REE), thorium (Th) and uranium (U) from monazite concentrate (MC) and phosphogypsum (PG). REE extraction from MC and their separation from Th and U are carried out from the product of MC–Na₂CO₃ baking (MCS), which is obtained under microwave irradiation, after which the phosphates of REE, Th and U present in the MC are converted into their oxides. Up to 50% of REE can be recovered as the adducts of TBP and D2EHPA with HNO₃ from the resulting powdered MCS under SCFE conditions, whereas Th and U remain in the solid phase. After a complete dissolution of the MCS residue in the mixture of 4 M HCl and 0.05 M HF, Th and U are quantitatively extracted using supercritical carbon dioxide (SC CO₂) containing D2EHPA and thus separated from the REE that remain in an acidic solution. The conditions of quantitative isolation of REE, Th and U from PG are determined. The schemes for complex processing of MC and PG aimed at REE recovery and their separation from Th and U are suggested.